Recently, there has been great interest in multi-input and multi-output (MIMO) systems, which use multiple antennas on both a transmitter side and a receiver side of a communication system to improve communication performance. For example, in a MIMO system, a base station may utilize multiple transmitting antennas to transmit data to a mobile station, and the mobile station may utilize multiple receiving antennas to receive the data.
Because there are multiple transmitting antennas and multiple receiving antennas in the MIMO system, a communication channel is established between each of the transmitting antennas and each of the receiving antennas. Accordingly, a plurality of communication channels are established between the base station and the mobile station.
In practice, the base station may need knowledge of information regarding the communication channels to improve throughput of the MIMO system. For example, the base station may perform bandwidth resource allocation and signal modulation based on the information regarding the communication channels. In addition, the base station may perform MIMO mode selection and pre-coder selection based on the information regarding the communication channels.
To facilitate improvement of throughput of the MIMO system, the mobile station may estimate information regarding the communication channels between the base station and the mobile station, i.e., channel state information (CSI), based on signals received from the base station, and then provide to the base station feedback of the estimated CSI.